First of all, search can be your friend.
http://www.chiefdelphi.com/forums/sh...hlight=letters
Secondly, since FIRST is not recognized by all High School Athletic Associations (currently only Minnesota's does) there is not a genaric and commonly used lettering method. It is up to each individual team on how they want to define the requirements.
For 1802 out of Piper High School the team sets standards at the begining of the year on what allows a student to letter and attend the regional. The regional standards have been adjusted after build season so we can actually take a medium sized team to the Regional because we do not make the students pick one activity over another.
They get the normal school letter the first year and a pin for every year they are apart of the team.